KR20120010182A - Image processing apparatus, image processing method, and program product - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing apparatus, an image processing method, and a program product. The contrast emphasis processing section 31 of the present invention sets a pixel of interest in the composite luminance component image data and performs a process of emphasizing contrast. In addition, the chroma enhancement processing unit 31 performs the overall chroma enhancement process on the composite chrominance component image data, and performs a partial emphasis process on the pixel of interest with an enhancement amount equal to the enhancement amount used in the contrast enhancement process. . The combined luminance component image and the composite chrominance component image subjected to the emphasis processing are combined to be image data after the emphasis processing, and the image data after the emphasis processing is supplied to the noise reduction unit 13 to reduce the noise.

Description

An image processing apparatus, an image processing method, and a program product {IMAGE PROCESSOR, IMAGE PROCESSING METHOD, AND PROGRAM PRODUCT}

TECHNICAL FIELD This invention relates to the technique of image processing stuck to the image etc. which enlarged the dynamic range, for example.

In recent years, various image processing is performed with respect to the image | photographed image in order to raise the directing effect at the time of appreciation.

Then, an image having different exposure conditions, which is introduced by Japanese Patent Application Laid-open No. 2006-345509 as such image processing, is synthesized in place, and whitening or shadowing occurs. Is a process for generating an image (hereinafter referred to as an HDR (High Dynamic Range) image) having no).

However, the above synthesis process aims at increasing the reproducibility of the imaging angle of view.

Therefore, in order to obtain an image in which each parameter of the color space is excessively adjusted and the reality is not lost, a new drawing process must be performed from the zero based on the captured image. .

Japanese Patent Application Publication No. 2006-345509

This invention is made | formed in view of such a situation, Comprising: It aims at generating each image which adjusts each parameter of a color space using a picked-up image, and does not lose a sense of reality.

In order to achieve the above object, in the first aspect of the present invention, an image processing apparatus for processing image data composed of luminance components and other components defined in a predetermined color space has the following configuration.

First emphasis processing means for processing first image data comprising luminance components among the image data to emphasize contrast using a predetermined first enhancement amount;

Second emphasis processing means for processing second image data including other components among the image data to emphasize saturation using the first emphasis amount used in the first emphasis processing means;

Image data acquisition means for acquiring new image data by combining first image data whose contrast is emphasized by the first emphasis processing means and second image data whose saturation is enhanced by the second emphasis processing means.

In order to achieve the above object, in the second aspect of the present invention, an image processing method for processing image data composed of luminance components and other components defined in a predetermined color space comprises the following steps.

A first emphasis processing step of processing first image data comprising luminance components among the image data to emphasize contrast using a predetermined first enhancement amount;

A second emphasis processing step of processing second image data consisting of other components among the image data to emphasize saturation using the first emphasis amount used in the first emphasis processing step,

An image data acquisition step of acquiring new image data by combining first image data in which contrast is emphasized in the first emphasis processing step and second image data in which saturation is enhanced in the second emphasis processing step.

In order to achieve the above object, a third aspect of the present invention is a program product that stores a program for processing image data composed of luminance components and other components defined in a predetermined color space by a computer. It also serves as the following means.

First emphasis processing means for processing first image data comprising luminance components among the image data to emphasize contrast using a predetermined first enhancement amount;

Second emphasis processing means for processing second image data including other components among the image data to emphasize saturation using a first emphasis amount used by the first emphasis processing means;

Image data acquisition means for acquiring new image data by combining first image data whose contrast is emphasized by the first emphasis processing means and second image data whose saturation is enhanced by the second emphasis processing means.

1 is a circuit configuration diagram of an imaging device according to an embodiment of the present invention.
2 is a functional block diagram showing a functional configuration of a function for executing the image processing process in the present invention.
3 is a flowchart illustrating an example of a flow of image processing performed by the image processing apparatus of FIG. 2.
4A to 4E are diagrams showing specific processing results by the combining unit of the image processing apparatus of FIG. 2.
FIG. 5 is a flowchart showing an example of the flow of luminance enhancement processing executed by the emphasis image generating unit of the image processing apparatus of FIG. 2.
6 is a flowchart illustrating an example of a flow of color difference emphasis processing executed by an emphasis image generating unit of the image processing apparatus of FIG. 2.
7A to 7D are diagrams showing an example of image data that is the object of the image processing process of FIG. 3.
FIG. 8 is a diagram showing an example of image data after emphasis processing, which is obtained as a result of performing the image processing process of FIG. 3 using each data of FIGS. 7A to 7D.
9 is a block diagram showing the hardware configuration of an image processing apparatus according to an embodiment of the image processing apparatus of the present invention.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

1 is a circuit configuration diagram of an imaging device having an image processing device according to an embodiment of the present invention.

The imaging device includes an imaging section 1, a drive control section 2, a CDS / ADC 3, a key input section 4, a display section 5, an image recording section 6, and a program memory ( 7), RAM 8, control unit 9, and image processing unit 10 are provided.

The key input unit 4 includes a shutter key 41 for detecting a recording instruction of the photographer. The image processing unit 10 includes a combining unit 11 corresponding to the characteristic configuration of the present invention. Moreover, it has the function of the image generation part 12 and noise reduction part 13 mentioned later.

Each of the above-described configurations is connected via a bus line.

In FIG. 1, the imaging part 1 is made into the light intensity by accumulating an electric charge by image sensor, such as a CMOS, the color filter of RGB provided on this image sensor, and the control from the drive control part 2. The driver is built in the CDS / ADC 3 so as to keep time and output these as analog imaging signals.

Then, the imaging unit 1 detects the photographing instruction of the photographer via the shutter key 41, the control unit 9, and the drive control unit 2, thereby exposing the exposure conditions (shutter speed or aperture value) while changing the exposure conditions. A plurality of images (color images) including underexposure image data, correct exposure image data, and overexposure image data are acquired.

The CDS / ADC 3 is a circuit into which an analog imaging signal corresponding to an optical image of the subject output from the imaging unit 1 is input. The CDS / ADC 3 includes a CDS for holding an input image signal, a gain adjustment amplifier (AGC) for amplifying the image signal, and an A / D converter (ADC) for converting the amplified image signal into a digital image signal. It is configured to include).

The control associated with the adjustment of the gain adjustment amplifier is also executed in accordance with the instruction from the drive control unit 2. Therefore, even when a plurality of images are acquired under the same exposure conditions, different images having a plurality of conditions can be generated by sequentially changing the RGB gain adjustment amplifier and the image hue of the image.

In addition to the shutter key 41 described above, the key input unit 4 is provided with various keys for detecting switching to a shooting mode, switching of display, etc. for the purpose of acquiring or recording an image according to the present invention.

The display unit 5 has a function of displaying the synthesized image.

The image recording unit 6 stores and stores the image data (image file) encoded by the JPEG system after the combining process according to the present invention is executed.

The program memory 7 stores a program executed by the control unit 9 and the image processing unit 10, and the control unit 9 reads the program if necessary.

The RAM 8 has a function of temporarily holding data in the process generated by various processes.

The control unit 9 controls the processing operation of the entire imaging device.

The image processing unit 10 includes a combining unit 11 for executing the combining process according to the present invention, in addition to the encoding / decoding process of the image data.

Next, a function for executing the image processing will be described using the functional block diagram of FIG. 2.

The image processing described in detail in this embodiment refers to a process of pixel-adding and synthesizing the images to be processed, and further highlighting contrast and vividness (saturation) after the composition.

In addition, in the said combining process, it passes through the imaging part 1 and the CDS / ADC 3, and is made to the plural image acquired by twisting while changing exposure conditions (shutter speed, aperture value, or gain adjustment value). For each of these image data, the luminance component and each of the three components of the luminance signal representing the Y component defined in the YUV color space, the blue color difference signal representing the other UV component, and the red color difference signal, respectively. The pixels are separated into chrominance components, pixel-added and synthesized for the plurality of luminance components after the separation, and pixel-added and synthesized for the plurality of chrominance components after separation.

Further, among the components of the three components of the luminance signal, the color difference signal U and the color difference signal V, the luminance signal of the HDR synthesized image data generated by the above-described synthesis process is executed to emphasize the contrast. For each color difference signal, a process of emphasizing saturation (sharpness) is performed separately.

In particular, in the above-described processing, the entire image is not simply emphasized with respect to contrast and saturation, but is emphasized pixel by pixel using an emphasis amount adaptively set in units of pixels.

In FIG. 2, the image processing apparatus includes a combining unit 11, an image generating unit 12, and a noise reduction unit 13.

In the present embodiment, as a plurality of image data each having different exposure conditions, as shown in FIG. 2, an image of an appropriate exposure value (hereinafter referred to as a "proper exposure value image") and an image of an exposure value exceeding an appropriate exposure value (hereinafter, " Data of the exposure value below the appropriate exposure value (hereinafter referred to as the "exposure value under image") is input to the combining unit 11.

Here, an appropriate exposure value does not necessarily mean an appropriate exposure value as a condition at the time of imaging, but means an intermediate exposure value between the two exposure values used when imaging each of an exposure value over image and an exposure value underimage.

The combining unit 11 generates HDR synthesized image data by pixel-adding each data of the appropriate exposure value image, the exposure value over image, and the exposure value under image.

The type of the synthesis processing performed by the combining section 11 is not particularly limited, but may be a synthesis process in which the dynamic range enlargement effect is enhanced as compared with a conventional synthesis process for generating HDR composite image data. .

The method of strengthening the effect is also not particularly limited, and for example, increases the difference (deviation) between the exposure value under and the exposure value over at the time of shooting, increases the number of shots, and other gain parameters such as color tone. It is possible to adopt a method such as changing the.

In this embodiment, the synthesizing unit 11 executes the following series of processes as the synthesizing process.

That is, in this embodiment, although not shown, the luminance component image data of the appropriate exposure value and the chrominance component image data of the appropriate exposure value separated from the appropriate exposure value image data are independently input to the combining section 11.

Similarly, the luminance component image data of the exposure value over and the chrominance component image data of the exposure value over which are separated from the exposure value over image data are independently input to the combining unit 11.

Similarly, the luminance component image data of the exposure value under and the chrominance component image data of the exposure value under which are separated from the exposure value under image data are independently input to the combining section 11.

The synthesizing section 11 generates the synthesized image data by pixel-adding and combining the luminance component image data of the appropriate exposure value, the luminance component image data of the exposure value over, and the luminance component image data of the exposure value under.

On the other hand, the combining unit 11 generates synthesized image data by pixel-adding and combining the color difference component image data of the appropriate exposure value, the color difference component image data of the exposure value over, and the color difference component image data of the exposure value under.

In the present embodiment, in the combining process of the luminance components, the luminance component image data of the appropriate exposure value, the luminance component image data of the exposure value over, and the luminance component image data of the exposure value under are pixel-added and synthesized according to a predetermined composition ratio.

The predetermined composition ratio means a mixing ratio of respective image data when two or more image data are pixel-added and synthesized.

For example, when the combination ratios of the luminance component image data of the appropriate exposure value, the luminance component image data of the exposure value over, and the luminance component image data of the exposure value under each are 70%, 30%, and 0%, the luminance of the appropriate exposure value Data obtained as a result of mixing at a ratio of 70% of the component image data, 30% of the luminance component image data over the exposure value and 0% of the luminance component image data at the exposure value under becomes the composite luminance component image data.

On the other hand, also in the chrominance component synthesis process, the chrominance component image data of the appropriate exposure value, the chrominance component image data of the exposure value over, and the chrominance component image data of the exposure value under are pixel-added and synthesized according to a predetermined composition ratio.

Here, as for the synthesis ratio used for the chrominance component synthesis processing, the synthesis ratio used for the luminance component synthesis processing is used as it is.

In this way, the combining unit 11 outputs a combination of the synthesized luminance component image data generated by the luminance component synthesis process and the synthesized color difference component image data generated by the chrominance component synthesis process.

The image generation unit 12 performs contrast enhancement processing on the composite luminance component image data output from the synthesis section 11, and saturation enhancement processing on the composite chrominance image data, respectively.

Here, contrast enhancement processing performed on the synthesized luminance component image data is referred to as contrast enhancement processing below. On the other hand, the saturation emphasis processing performed on the composite color difference component image data is referred to as saturation emphasis processing below.

The image generating unit 12 is provided with a contrast enhancement processing unit 31 for performing contrast enhancement processing and a chroma enhancement processing unit 32 for executing chroma enhancement processing for executing chroma enhancement processing.

The contrast enhancement processing unit 31, as contrast enhancement processing, performs unsharp mask processing in two kinds of frequency bands (for example, low and mid range) with respect to the composite luminance component image data. By performing mask processing respectively, the contrast is emphasized locally.

When the unsharp mask processing is performed in two kinds of frequency bands (for example, low and mid range), smoothing of the composite luminance component image data is performed.

The filter to be used for such smoothing is not particularly limited, and a general LPF (Low Pass Filter) may be employed, but nonlinear filters such as an edge retention type ε filter and a bilateral filter are preferably employed.

The contrast enhancement processing section 31 includes a synthesized luminance component image acquisition section 41, an ε filter section 42A, 42B, a contrast component creating section 43A, 43B, a contrast combining section 44, and contrast enhancement. The part 45 is provided.

The function and the like of each element of the contrast emphasis processing section 31 will be described as appropriate when explaining the flow of the contrast emphasis processing with reference to the flowchart of FIG. 3 described later.

The saturation emphasis processing unit 31 executes a process of emphasizing saturation, using a predetermined gain (hereinafter referred to as "UV gain") as the amount of emphasis on the image data of the synthesized color difference component.

In this case, the process of emphasizing saturation is roughly divided into two types, the whole emphasis process and the partial emphasis process.

The whole emphasis process refers to a process of emphasizing saturation to make the impression of the entire image colorful.

The partial emphasis process refers to a process of emphasizing saturation using an emphasis amount linked with an enhancement amount of a synthetic contrast component used in the contrast enhancement process.

In the following, the enhancement amount for contrast enhancement processing is referred to as "contrast component enhancement amount". On the other hand, the emphasis amount for chroma component emphasis processing is called "saturation component emphasis amount".

The saturation component enhancement amount is further divided into the enhancement amount used in the entire emphasis process and the enhancement amount used in the partial emphasis process, and the former is hereinafter referred to as "the overall saturation component enhancement amount", and the latter is hereinafter referred to as " Partial saturation component emphasis.

In addition, a series of processing by the saturation emphasis processing part 32 is called "saturation emphasis processing" hereafter.

The saturation enhancement processing unit 32 performs a chroma enhancement image processing unit 51, an overall saturation enhancement unit 52, a contrast component enhancement amount acquisition unit 53, and partial saturation in order to execute chroma enhancement processing. The emphasis 54 is provided.

In addition, the image generation unit 12 is provided with an image acquisition unit 33 after the emphasis processing.

After the emphasis processing, the image acquiring section 33 includes the image data of the synthesized luminance component subjected to the contrast enhancement processing by the contrast emphasis processing section 31 and the image of the synthesized color difference component subjected to the chroma enhancement processing by the chroma enhancement processing section 32. Image data after the emphasis processing made of a combination of data is acquired.

After the emphasis processing, the image data after the emphasis processing acquired by the image acquisition unit 33 is supplied to the noise reduction unit 13.

The noise reduction unit 13 performs noise reduction processing on the image data after the emphasis processing.

Next, with reference to the flowchart of FIG. 3, the image processing process performed by the image processing apparatus of FIG. 2 which has such a functional structure is demonstrated.

3 is a flowchart showing an example of the flow of an image processing process.

In step S1, the combining unit 11 acquires plural image data each having different exposure values obtained by continuous shooting or the like.

In step S2, the combining unit 11 generates the combined image data of the high dynamic range by pixel-adding the plurality of image data having different exposure values, respectively.

Specifically, in the present embodiment, each data of the appropriate exposure value image, the exposure value over image, and the exposure value under image is acquired in the process of step S1, and pixel-added and synthesized by the process of step S2, so as to achieve high dynamic range. Synthetic image data is generated.

4A to 4E show the specific processing results of steps S1 and S2 by the combining unit 11.

4A illustrates an example of image data of the luminance component of the exposure value under acquired in the process of step S1.

4B illustrates an example of image data of luminance components of appropriate exposure values obtained in the process of step S1.

4C shows an example of the luminance component image data of the exposure value over obtained in the process of step S1.

FIG. 4D shows an example of synthesized image data obtained as a result of pixel addition synthesis of each data in FIGS. 4A to 4B in the process of step S2.

4E shows an example in the case where the effect of the synthesis is stronger than in FIG. 4D.

As described above, by intensifying the effect of compositing, the effect of obtaining a high dynamic range synthesized image that does not lose reality even if each parameter of the color space is excessively adjusted is remarkable.

Therefore, in the present embodiment, the composite image data of FIG. 4E is given to the image generating unit 12 as a processing target among the composite image data of FIGS. 4D and 4E. It is assumed that the process after step S3 in FIG. 3 is executed.

In step S3, the contrast enhancement processing unit 31 of the image generation unit 12 performs contrast enhancement processing on the composite luminance component image data among the synthesized image data generated by the process of step S2.

In step S4, the chroma enhancement processing unit 31 of the image generating unit 12 performs chroma enhancement processing on the image data of the synthesized color difference component among the synthesized image data generated by the process of step S2.

The details of the contrast enhancement process of step S3 will be described later by referring to the flowchart of FIG. 5 and the details of the chroma enhancement process of step S4 by referring to the flowchart of FIG. 6.

In step S5, the image acquisition unit 33 after the emphasis processing combines the image data of the synthesized luminance component subjected to the contrast enhancement processing of step S3 with the image data of the synthesized color difference component subjected to the chroma enhancement processing of Step S4. The image data is obtained as image data after the emphasis processing.

In step S6, the noise reduction unit 13 performs a noise reduction process on the image data after the emphasis processing acquired in the process of step S5.

When the image data after the emphasis processing in which the noise reduction processing has been performed is output from the noise reduction unit 13 to the outside, the image processing processing ends.

Next, details of the contrast enhancement process of step S3 and the saturation emphasis process of step S4 are individually described in this order among such image processing processes.

First, with reference to the flowchart of FIG. 5, the contrast emphasis process of step S3 is demonstrated in detail.

5 is a flowchart showing an example of the flow of contrast enhancement processing.

In step S21, the composite luminance component image acquisition unit 41 of the contrast emphasis processing unit 31 in FIG. 2 acquires the composite luminance component image data among the composite image data output from the combining unit 11.

In step S22, the contrast enhancement processing unit 31 selects pixels arranged at predetermined positions (coordinates) among the pixels constituting each of the synthesized luminance component images as pixels to be processed (hereinafter referred to as "focus pixels"). Set).

If data (pixel values) of the pixel of interest of the synthesized luminance component image are supplied to each of the? Filter sections 42A and 43A and the contrast creating sections 43A and 43B, the process proceeds to step S23.

In step S23, the epsilon filter units 42A and 43A and the contrast component creating units 43A and 43B are formed of two kinds of frequencies (medium and low) from the data (pixel values) of the pixel of interest of the synthesized luminance component image. Using two epsilon filters, two kinds of contrast components of the pixel of interest are created.

In this embodiment, the component is generated using one of the two types of contrasts that are the components to be created using a mid-weighted epsilon filter having a small filter size.

Here, this kind of contrast is referred to as "medium contrast".

On the other hand, about the other of the two types of contrast, the component is produced using the low intensity (epsilon) filter with a large filter size.

Here, such a kind of contrast is referred to as "low contrast".

In the present embodiment, the midrange contrast is generated by the? Filter section 42A and the contrast component creating section 43A by performing the following series of processes.

That is, the ε filter unit 42A processes the data of the pixel of interest in the composite luminance component image with the ε filter of the midpoint emphasis, and the resulting data (hereinafter referred to as "filtering data") is a contrast creation unit. It supplies to 43A.

The contrast component creating unit 43A creates a contrast component for the pixel of interest of the pixel of interest by taking a difference between the data of the pixel of interest of the synthesized luminance component image and the data after the filtering process of the pixel of interest.

In detail, the following formula (1) is calculated, and the contrast component for pixel range of interest is created.

Y_contrast_1 = Y_HDR-Y_ε_1... (One)

In formula (1),

Y_contrast_1 represents the pixel contrast contrast of interest.

Y_HDR represents data (pixel value) of the pixel of interest of the HDR composite Y image.

Y_ε_1 shows the data after the filtering process of the pixel of interest produced | generated using the epsilon filter for midrange.

On the other hand, in the present embodiment, the low contrast is generated by the ε filter portion 42B and the contrast component creating portion 43B by performing the following series of processes.

That is, the epsilon filter part 42B processes the data of the pixel of interest of the synthesized luminance component image with the epsilon filter of low frequency emphasis, and supplies the data after the filtering process obtained as a result to the contrast component creation part 43B.

The contrast component creating unit 43B creates a low contrast component for the pixel of interest by taking a difference between the data of the pixel of interest of the synthesized luminance component image and the data after the filtering process of the pixel of interest.

That is, the following formula (2) is calculated, and the low contrast contrast component of the pixel of interest is created.

Y_contrast_2 = Y_HDR-Y_ε_2... (2)

In formula (2),

Y_contrast_2 represents the low contrast component of the pixel of interest.

Y_HDR represents data (pixel value) of the pixel of interest in the composite luminance component image.

Y_ε_2 shows the data after the filtering process of the pixel of interest produced | generated using the lowpass epsilon filter.

Two kinds of contrasts of the pixel of interest generated in this manner, that is, the pixel intermediate contrast component generated by the contrast creating unit 43A and the low pass contrast component of the pixel of interest generated by the contrast creating unit 43B Supplied to the contrast synthesis section 44. In this way, the process proceeds to step S24 of FIG. 5.

In step S24, the contrast synthesizing section 44 adds and synthesizes two kinds of contrast components of the pixel of interest, namely, the pixel mid-range contrast component and the low-pass contrast component of the pixel of interest, thereby creating a composite contrast component of the pixel of interest.

That is, the compound contrast of the pixel of interest is created by calculating the following equation (3).

Y_contrast = Y_contrast_1 + Y_contrast_2... (3)

In formula (3),

Y_contrast represents the composite contrast component of the pixel of interest.

Y_contrast_1 represents the contrast component for pixel midrange of interest computed by the above-mentioned Formula (1).

Y_contrast_2 represents the low-pass contrast component of the pixel of interest computed in the above formula (2).

In this way, the combined contrast component of the pixel of interest generated by the contrast combining section 44 is supplied to the contrast emphasis section 45. In this way, the process proceeds to step S25 of FIG. 5.

In step S25, the contrast emphasis unit 45 adjusts and restricts the combined contrast component of the pixel of interest.

Specifically, in the present embodiment, the adjustment to the composite contrast component of the pixel of interest is performed according to the following equation (4).

Y_contrast = Y_contrast × (Y_gain_lev / 100) × (Y_adj_lev / 100)... (4)

In formula (4),

The Y_contrast on the left side represents the composite contrast component of the pixel of interest after the adjustment.

On the other hand, Y_contrast on the right side represents the composite contrast component of the pixel of interest before adjustment.

In Equation (4), Y_gain_lev represents the level (%) of gain (hereinafter, referred to as "luminance component gain") uniformly set for the entire composite luminance component image data.

On the other hand, Y_adj_lev represents the level (%) of the adjustment amount (hereinafter referred to as "luminance component adjustment amount") set individually for the data of the pixel of interest in the composite luminance component image.

The luminance component adjustment amount Y_adj_lev is set individually for each pixel of the composite luminance component image according to the data (pixel value) Y_HDR.

Therefore, for each pixel set as the pixel of interest, the luminance component adjustment amount Y_adj_lev is adaptively changed in accordance with the data (pixel value) Y_HDR, and as a result, the composite contrast component Y_contrast is adaptively adjusted for each pixel.

As a result, adverse effects due to saturation of the pixel value due to contrast enhancement, for example, blackening, whitening, color saturation, and the like, can be reduced.

In addition, in the present embodiment, the restriction on the composite contrast component of the pixel of interest is performed according to the following formula (5) when the composite contrast component of the pixel of interest is less than zero (If (Y_contrast> 0)). Else is performed according to the following equation (6).

Y_contrast = fMin (Y_contrast, Y_contrast_max_lev)... (5)

Y_contrast = fMax (Y_contrast, Y_contrast_max_lev |)... (6)

In formula (5) and formula (6),

The Y_contrast on the left side represents the composite contrast component of the pixel of interest after limitation.

On the other hand, Y_contrast on the right side represents the composite contrast component of the pixel of interest before restriction.

In addition, in Formula (5) and Formula (6), Y_contrast_max_lev has shown the upper limit level preset as a synthetic contrast component.

FMin ((alpha), (beta)) in Formula (5) has shown the function which outputs the minimum value of (alpha) and (beta).

In addition, fMax ((alpha), (beta)) in Formula (6) has shown the function which outputs the maximum value of (alpha) and (beta).

Next, in step S26 of FIG. 5, the contrast emphasis unit 45 adds the composite contrast of the pixel of interest after the adjustment and restriction are performed in the processing of step S25 to the data of the pixel of interest of the composite luminance component image. .

Thus, the contrast is emphasized only for the composite contrast component of the pixel of interest whose adjustment and limitation have been performed in the process of step S25 for the data of the pixel of interest of the composite luminance component image.

Specifically, by calculating the following equation (7), the contrast is emphasized with respect to the data of the pixel of interest of the composite luminance component image.

Y_result = Y_HDR + Y_contrast… (7)

In formula (7),

Y_result represents data of the pixel of interest after the contrast enhancement process (pixel value of the pixel of interest after the contrast enhancement process).

On the other hand, Y_HDR represents data of the pixel of interest before the contrast enhancement process (pixel value of the pixel of interest before the contrast enhancement process).

In addition, Y_contrast represents the amount of contrast component emphasis as a composite contrast component of the pixel of interest after the adjustment by Expression (4) and the restriction by Expression (5) or Expression (6) is performed.

In step S27, the contrast emphasis processing unit 31 determines whether all pixels have been set as the pixel of interest.

If there is a pixel that has not yet been set as the pixel of interest among the pixels constituting the synthesized luminance component image, it is determined as NO in Step S27, the processing returns to Step S22, and the subsequent processing is repeated.

That is, whenever the pixels constituting the composite luminance component image are sequentially set as the pixel of interest, the loop processing of steps S22 to S27 is repeatedly executed, so that the data of the pixel set as the pixel of interest is continuously updated so that the contrast is emphasized. .

However, as described above, the emphasis level of the contrast is adaptively changed in accordance with the value of the data Y_HDR before updating of the pixel set as the pixel of interest.

Then, when the last pixel is set to the pixel of interest in the process of step S22, and the processes of steps S23 to S26 are executed, all the pixels constituting the synthesized luminance component image have been updated. Since the value Y_result has been updated to 7), it is determined as YES in the next step S27, and the contrast emphasis process ends.

Thereby, the contrast enhancement process of step S3 is complete | finished during the image processing process of FIG. 3, and the saturation emphasis process of step S4 is performed.

Here, with reference to the flowchart of FIG. 6, the saturation emphasis process of step S4 is demonstrated in detail.

6 is a flowchart showing an example of the flow of chroma enhancement processing.

In step S41, the composite chrominance component image acquisition unit 51 of the chroma component enhancement processing unit 31 in FIG. 2 acquires the image data of the composite chrominance component among the composite image data output from the synthesis unit 11.

In step S42, the saturation emphasis processing unit 31 sets, as the pixel of interest, a pixel disposed at a predetermined position (coordinate) among the pixels constituting each of the composite chrominance component images.

Here, in the present embodiment, the chroma enhancement processing section 31 is executed asynchronously with the emphasis section 32, but the pixel of interest of the composite chrominance component image and the pixel of interest of the composite luminance component image are located at the same position (coordinate). The following description will be given as corresponding pixels, respectively.

In step S43, the overall saturation emphasis unit 52 performs an overall saturation enhancement process using the overall saturation component enhancement amount on the image data of interest of the composite chrominance component image.

Specifically, in the present embodiment, the following equations (8) and (9) are calculated, so that the overall chroma enhancement process is performed on the image data of interest of the composite color difference component image.

U_HDR '= U_HDR x UV_gain_lev_al / 100... (8)

V_HDR '= V_HDR x UV_gain_lev_al / 100... (9)

In formula (8),

U_HDR 'represents the color difference component value (U component value) of the image of interest of the synthesized color difference component image after the overall chroma enhancement process is performed.

On the other hand, U_HDR represents the color difference component value (U component value) of the image of interest of the composite color difference image before the overall chroma enhancement process is performed.

In formula (9),

V_HDR 'represents the color difference component value (V component value) of the image of interest of the synthesized color difference image after the overall chroma enhancement process is performed.

On the other hand, V_HDR represents the color difference component value (V component value) of the image of interest in the composite color difference component image before the overall chroma enhancement process is performed.

In the formulas (8) and (9), UV_gain_lev_al represents the total gain (%) as the emphasis amount of the overall saturation component set uniformly on the entire composite color difference image.

In step S44, the contrast component enhancement amount acquisition unit 53 acquires the enhancement amount of the contrast component used for the pixel of interest in the composite luminance component image in the previous contrast enhancement processing.

Specifically, following formula (10) is calculated and the contrast component emphasis amount is acquired.

Y_emphasis_Lev = | Y_contrast | … 10

In formula (10),

The Y_emphasis_Lev on the left side represents the acquired contrast component enhancement amount.

The right side Y_contrast is a composite contrast component of the pixel of interest after the adjustment by Expression (4) described above and the restriction by Expression (5) or Expression (6) is performed. It is a correction amount added to the data (pixel value Y_HDR) of the preceding pixel of interest.

In step S44, the partial saturation emphasis unit 54 is linked to the contrast component emphasis amount acquired in the processing of step S43, with respect to the image data of interest of the composite chrominance component image in which the overall saturation emphasis processing has been performed in step S42. A partial chroma enhancement process is performed using the partial chroma component enhancement amount.

Specifically, in the present embodiment, the following equation (11) is calculated to perform partial chroma enhancement processing on the U component values of the image of interest of the synthesized color difference component image on which the overall chroma enhancement processing is performed.

U_result = U_HDR '

     + U_HDR × (UV_gain_lev_part × Y_emphasis_lev / Y_contrast_max_lev) / 100

     X UV_adj_lev / 100... (11)

In formula (11),

The U_result on the left side represents the U component value of the image of interest in the synthesized color difference component image in which the overall chroma enhancement process and the partial chroma enhancement process are performed.

U_HDR 'on the right side represents the U component value of the image of interest of the composite chrominance component image after the overall saturation enhancement process is performed by the above-described formula (8).

U_HDR 'represents the U component value of the image of interest of the composite chrominance component image after the overall chroma enhancement process is performed by the above-described formula (8).

UV_gain_lev_part represents partial gain (%).

Y_emphasis_lev represents the amount of contrast component enhancement obtained by the above formula (10).

Y_contrast_max_lev represents the upper limit level preset as a composite contrast component.

(UV_gain_lev_part × Y_emphasis_lev / Y_contrast_max_lev) / 100 represents the partial saturation enhancement amount (%) linked with the contrast enhancement amount.

UV_adj_lev represents the level (%) of the adjustment amount (hereinafter referred to as "color difference adjustment amount") set individually for the data of the pixel of interest of the composite chrominance component image.

As shown in equation (12), the composite color difference component image data UV_HDR adopts the larger of the absolute values of the U component value U_HDR and the V component value V_HDR.

UV_HDR = fmax (| U_HDR |, | V_HDR |)... (12)

In Formula (12), fmax ((alpha), (beta)) has shown the function which outputs the maximum value of (alpha) and (beta).

The color difference adjustment amount UV_adj_lev is individually set for each pixel of the composite color difference component image according to the data (pixel value) UV_HDR.

Therefore, for each pixel set as the pixel of interest, the color difference adjustment amount UV_adj_lev is adaptively changed in accordance with the data (pixel value) UV_HDR.

As a result, the degree of partial chroma enhancement for the U component U_HDR of the target image is also adaptively adjusted for each pixel. As a result, adverse effects due to saturation of the pixel value due to saturation emphasis, for example, blackening, whitening, color saturation, and the like, can be reduced.

In the present embodiment, the following equation (13) is calculated to perform partial chroma enhancement processing on the V component values of the image of interest of the composite color difference component image on which the overall chroma enhancement processing is performed.

V_result = V_HDR '

 + V_HDR × (UV_gain_lev_part × Y_emphasis_lev / Y_contrast_max_lev) / 100

X UV_adj_lev / 100... (13)

In formula (13),

The V_result on the left side represents the V component values of the image of interest in the composite color difference component image on which the full emphasis process and the partial emphasis process have been performed.

The right side V_HDR 'represents the V component value of the image of interest of the synthesized chrominance component image after the overall saturation enhancement process is performed by the above formula (9).

V_HDR 'represents the V component value of the image of interest of the composite chrominance component image after the overall chroma enhancement process is performed by the above formula (9).

Also in (13), (UV_gain_lev_part × Y_emphasis_lev / Y_contrast_max_lev) / 100 is used as the partial saturation enhancement amount (%) in conjunction with the contrast component enhancement amount, similarly to equation (11).

In addition, also in Formula (13), the color difference adjustment amount UV_adj_lev is used similarly to Formula (11).

In step S46 of FIG. 6, the saturation emphasis processing unit 31 determines whether all pixels have been set as the pixel of interest.

If there is a pixel which is not yet set as the pixel of interest among the pixels constituting the composite chrominance component image, it is determined as NO in Step S46, the processing returns to Step S42, and the subsequent processing is repeated.

That is, whenever the pixels constituting the composite chrominance image are sequentially set as the pixel of interest, the loop processing of steps S42 to S46 is repeatedly executed, so that the data of the pixel set as the pixel of interest is continuously updated so that the saturation is emphasized.

However, as described above, the degree of enhancement of the saturation is adaptively changed in accordance with the values of the data U_HDR and V_HDR before updating the pixel set as the pixel of interest, in conjunction with the degree of contrast enhancement.

Then, when the last pixel is set as the pixel of interest in the process of step S42, and the processes of steps S43 to S46 are executed, all the pixels constituting the composite chrominance component image have been updated. The value U_result of 11) and the value V_result of the formula (13)] are determined to be YES in the next step S46, and the chroma enhancement processing ends.

Thereby, in the image processing process of FIG. 3, the saturation emphasis process of step S4 is complete | finished, and a process progresses to step S5. That is, the combination of the image data of the synthesized luminance component subjected to the contrast enhancement processing in step S3 and the image data of the synthesized color difference component subjected to the saturation enhancement processing in step S4 is the image data after the emphasis processing. 33).

As described above, when the synthesized image data is separated into synthesized luminance component image data composed of luminance components and synthesized chrominance component image data composed of chrominance components, the contrast enhancement processing section 31 of FIG. The component enhancement amount is used to emphasize the contrast of the image data of the composite luminance component.

On the other hand, the chroma enhancement processing unit 31 processes to emphasize the chroma of the image data of the synthesized color difference component using the chroma enhancement amount that is variable in conjunction with the contrast component enhancement amount of the contrast enhancement processing unit 31.

In this way, it is possible to obtain an effect of obtaining composite image data of high dynamic range that does not lose reality even when each parameter of the color space is excessively adjusted.

In particular, the contrast enhancement processor 31 emphasizes the contrast by using contrast component enhancement amounts different for each position of the data of pixels at predetermined positions (coordinates) in the image of the synthesized luminance component, and then saturation enhancement processor ( 31) uses a saturation component enhancement amount that varies in conjunction with a contrast component enhancement amount for a position in the same composite luminance component image as that of the position (coordinate), to determine a pixel at a predetermined position (coordinate) in the composite chrominance component image. By saturation emphasizing the data, the above effect becomes remarkable.

Such an effect can be clearly seen by referring to Figs. 7A to 7D and Fig. 8.

7A to 7D show an example of image data which is the object of the image processing in FIG. 3, and shows the same data as the example of FIG. 4E.

FIG. 7A shows an example of synthesized image data obtained as a result of the process of step S2.

FIG. 7B shows that in the contrast enhancement process of step S3, an ε filter [33 x 33 (pixel) size] for mid-range contrast component emphasis is performed on the entire composite image data of FIG. 7A. An example of the data (see step S23 in FIG. 5) after the filtering of the entire image obtained as a result is shown.

FIG. 7C shows that in the contrast enhancement process of step S3, the entire composite image data of FIG. 7A is processed with an ε filter (size of 129 x 129) for low contrast contrast component enhancement. An example of the data after the filtering process of the entire image obtained as a result (see step S23 in FIG. 5) is shown.

FIG. 7D shows the contrast components of the entire image generated using the data of FIGS. 7A to 7C in the contrast enhancement process of step S3 (see steps S24 and S25 of FIG. 5). An example is shown.

FIG. 8 shows an example of the image data after the emphasis processing, which is obtained as a result of the image processing processing of FIG. 3 being performed using the data of FIGS. 7A to 7E, and the image after the emphasis processing has a color. It can be seen that it is a composite image that does not lose reality even if each parameter of the space is excessively adjusted.

In addition, this invention is not limited to the said Example, A deformation | transformation, improvement, etc. in the range which can achieve the objective of this invention are included in this invention.

For example, in the above-described embodiment, in the contrast enhancement process performed by the contrast enhancement processing section 31, the ε filter is employed as a filter used for smoothing.

However, as described above, it is not particularly limited to the ε filter, and for example, it is intended to generate an image intentionally indicating undershoot or overshoot that occurs when the contrast component is locally emphasized. In this case, ordinary LPF may be employed.

For example, in the above-mentioned embodiment, although two types of frequencies (low range and mid range) are employ | adopted in contrast enhancement process for emphasizing contrast, it is not limited to this especially, Three or more types may be sufficient. For example, in addition to the low range and the mid range, by adopting a high range further, the high range can be emphasized to improve the sharpness.

Incidentally, in the above-described embodiment, although the face image area exists and is not considered in the image to be processed in the partial saturation enhancement process, the face image area is detected using a known face image area detection technique. In consideration of the presence of the detected face image, a partial saturation emphasis process with a small amount of emphasis may be performed. In this way, the problem of losing color and texture of the skin color component of the face due to excessive emphasis can be solved by this process.

More specifically, when the face image region is detected, the amount of contrast component enhancement applied to the luminance component image of the detected face image region and the amount of chroma component enhancement applied to the chrominance component image are set in advance.

The amount of these enhancements is less than the amount of contrast component enhancement and saturation component enhancement described so far, and may be suppressed to about 80% in detail.

When the face image area is detected, the image partially processed by the contrast enhancement amount and the saturation component enhancement amount in steps S3 to S4 described above, and the contrast component enhancement amount and the saturation component applied when the face image area is detected. An image with partial emphasis is generated by the emphasis amount.

Furthermore, these images are alpha-blended (processing by adjusting and adjusting the permeability) for each pixel to obtain a composite image.

In this case, the detected face image region and its surrounding region are synthesized so that the ratio of the partially emphasized image is increased by the contrast component enhancement amount and chroma component enhancement amount applied when the face image area is detected. The area can be synthesized so that the ratio of the image partially emphasized by the contrast enhancement amount and the saturation component enhancement amount in steps S3 to S4 described above is increased.

For example, in the above-mentioned embodiment, although three pieces of image data are pixel-added as plural image data with different exposure values, the number of image data to be synthesized is not particularly limited thereto. That is, the present invention can be widely applied to the case of pixel addition synthesis of any number of image data of two or more sheets.

In addition, the various image data made into the object of image processing is not specifically limited to the specific example shown in each above-mentioned figure. For example, the setting of the exposure value at the time of imaging the multiple image data used as a synthesis object is not limited to the specific example shown in each above-mentioned figure, You may arbitrarily as long as exposure value differs, respectively.

In addition, although not specifically mentioned in the above-mentioned embodiment, it is preferable that the position shift is correct | amended previously in consideration of pixel-added synthesis | combination of several image data from which exposure values differ, respectively.

For example, in the above-mentioned embodiment, the image processing apparatus to which the present invention is applied has been described as an example configured as a digital camera.

However, the present invention is not particularly limited to this, and can be generally applied to an electronic device having an image processing function. For example, the present invention is a digital photo frame, a personal computer, a portable navigation device, a portable game machine, or the like. It is widely applicable.

In other words, the above-described series of processes may be executed by hardware or may be executed by software.

9 is a block diagram showing a hardware configuration of an image processing apparatus to which the present invention is applied when the series of processes described above are executed by software.

In the example of FIG. 9, the image processing apparatus includes a CPU (Central Processing Unit) 201, a ROM (Read Only Memory) 202, a RAM (Random Access Memory) 203, a bus 204, An input / output interface 205, an input unit 206, an output unit 207, a storage unit 208, a communication unit 209, and a drive 210 are provided.

The CPU 201 executes various processes in accordance with the program recorded in the ROM 202. Alternatively, the CPU 201 executes various processes in accordance with a program loaded from the storage unit 208 into the RAM 203.

The RAM 203 also appropriately stores data required for the CPU 201 to execute various processes.

For example, in this embodiment, a program for realizing the functions of the synthesizing unit 11 or the noise reduction unit 13 is stored in the ROM 202 or the storage unit 208. Therefore, the CPU 201 can realize the functions of the combining unit 11 or the noise reduction unit 13 by executing the processing according to these programs.

The CPU 201, the ROM 202, and the RAM 203 are connected to each other via the bus 204. The bus 204 is further connected with an input / output interface 205. An input unit 206, an output unit 207, a storage unit 208, and a communication unit 209 are connected to the input / output interface 205.

The input part 206 is comprised by operation parts, such as various buttons, and accepts a user's instruction operation, and inputs various information.

The output unit 207 outputs various kinds of information. For example, the display part which is not shown in figure is provided in the output part 207, and the composite image represented by the output data of the combining part 11 is displayed.

The storage unit 208 is configured of a hard disk, a dynamic random access memory (DRAM), or the like, and stores various data.

The communication unit 209 controls communication performed with other devices (not shown) via a network including the Internet.

The drive 210 is further connected to the input / output interface 205 as necessary, and a removable medium 211 made of a magnetic disk, an optical disk, a magneto-optical disk, a semiconductor memory, or the like is appropriately mounted. The program read out from the removable media 211 by the drive 210 is installed in the storage unit 208 as necessary. The removable media 211 can also store various data such as image data stored in the storage unit 208, similarly to the storage unit 208.

When a series of processes are performed by software, the program which comprises this software is installed in a computer etc. from a network or a recording medium. The computer may be a computer built in dedicated hardware. The computer may be a computer that can execute various functions by installing various programs, for example, a general purpose personal computer.

The recording medium including such a program is not only constituted by the removable media 211 distributed separately from the apparatus main body for providing the program to the user, but also the recording medium provided to the user in a pre-built state in the apparatus main body. Media and the like. The removable media 211 is composed of, for example, a magnetic disk (including a floppy disk), an optical disk, a magneto-optical disk, or the like. The optical disk is composed of, for example, a compact disk-read only memory (CD-ROM), a digital versatile disk (DVD), or the like. The magneto-optical disk is comprised by MD (Mini-Disk) etc. The recording medium provided to the user in a state of being pre-built in the apparatus main body includes, for example, a ROM 202 in which a program is recorded, a hard disk included in the storage unit 208, or the like.

In the present specification, the step of describing a program recorded on the recording medium includes not only processing performed in time series according to the order, but also processing executed in parallel or separately, without necessarily processing in time series. It is.

Claims (9)

An image processing apparatus for processing image data composed of luminance components defined in a predetermined color space and other components,
First emphasis processing means for processing first image data comprising luminance components among the image data to emphasize contrast using a predetermined first enhancement amount;
Second emphasis processing means for processing second image data including other components among the image data to emphasize saturation using the first emphasis amount used by the first emphasis processing means; And
Image data acquisition means for acquiring new image data by combining first image data whose contrast is emphasized by the first emphasis processing means and the second image data whose saturation is enhanced by the second emphasis processing means.
Image processing apparatus comprising a. The method of claim 1,
The first emphasis processing means processes the data of the pixel at a predetermined position in the first image to emphasize contrast using the first emphasis amount different for each position,
The second emphasis processing means converts the data of the pixel at a predetermined position in the second image into the second emphasis amount that is changed in conjunction with the first emphasis amount for a position in the first image that is the same as the position. And processing to emphasize saturation. The method of claim 2,
The second emphasis processing means,
Overall saturation enhancement processing means for processing saturation by applying the third enhancement amount which is applied to the data of the pixel at the predetermined position in the second image as a whole; And
Acquisition means for acquiring the second enhancement amount that changes in conjunction with the first enhancement amount for a position in the first image that is equal to the predetermined position.
Including,
The saturation enhancement processing by the overall saturation enhancement processing means and the saturation enhancement processing of the data of pixels at predetermined positions in the second image using the second enhancement amount acquired by the acquisition means. An image processing apparatus which processes to emphasize the saturation of the second image data composed of the component. The method of claim 1,
Image area detection means for detecting a face image area from the image data to be processed;
When the face image area is detected by the image area detection means, the first emphasis means emphasizes the contrast of the first image data by using a fourth emphasis amount less than the predetermined first emphasis amount,
And said second emphasis means emphasizes saturation of said second image data using a fifth emphasis amount that changes in conjunction with said fourth emphasis amount of said first emphasis means. The method of claim 4, wherein
And the first emphasis means for emphasizing the contrast of the peripheral portion of the face image area in the first image data. The method of claim 4, wherein
And the second emphasizing means emphasizes the saturation of a portion around the face image area in the second image data. The method of claim 1,
The image data composed of the luminance component defined in the predetermined color space and other components is image data obtained by enlarging the dynamic range generated by synthesizing a plurality of images photographed with different exposure conditions. An image processing method for processing image data composed of luminance components and other components defined in a predetermined color space,
A first emphasis processing step of processing first image data comprising luminance components among the image data to emphasize contrast using a predetermined first enhancement amount;
A second emphasis processing step of processing second image data consisting of other components among the image data to emphasize saturation using the first emphasis amount used by the first emphasis processing step; And
An image data acquisition step of acquiring new image data by combining the first image data whose contrast is emphasized in the first emphasis processing step and the second image data whose saturation is enhanced in the second emphasis processing step.
Image processing method comprising a. As a program product that stores a program for processing image data composed of luminance components and other components defined in a predetermined color space by a computer,
The computer,
First emphasis processing means for processing first image data comprising luminance components among the image data to emphasize contrast using a predetermined first enhancement amount;
Second emphasis processing means for processing second image data consisting of other components among the image data to emphasize saturation using the first emphasis amount used in the first emphasis processing means; And
Image data acquisition means for acquiring new image data by combining the first image data whose contrast is emphasized by the first emphasis processing means and the second image data whose saturation is enhanced by the second emphasis processing means.
Program product to function as.

Images